The Johns Hopkins Breast Human Specimen Resource and Database Core is an interdepartmental collaborative effort designed to support multi- disciplinary basic and translational research on the etiology, early detection, prevention and treatment of breast cancer and its precursor. The Core was designed using strategies that have proved successful in establishing tissue banks within the Department of Pathology and Core facilities for SPORE grants in gastrointestinal, prostate and pulmonary carcinoma at our institution. The Core provides flexible specimen collection techniques with quality assurance measures, inventory and tracking, collection of breast cancer risk factor information using questionnaire based on validated instruments and a secure relational database for storing and retrieving data with back-up files. Storage of frozen specimens, laboratory processing and data management will be performed in dedicated facilitated located in the newly constructed John Hopkins Cancer Center in immediate proximity to the operating rooms, surgical pathology laboratory, and research laboratories. The Core is designed to collect frozen breast tissue and cells, blood components, nipple fluid aspirates and other biological specimens. The Core is directed by an experienced pathologist with expertise in breast and gynecologic pathology and molecular epidemiology and will be staffed by trained technical personnel who report to the Director. The Co-PI of the Core is an experienced surgical pathologist and molecular biologist who has a special interest in breast cancer. The Core is a prospective collection of data and specimens donated by patients who either present to Johns Hopkins for initial diagnostic evaluation or have been referred to Hopkins following a diagnosis at another institution. Patients are recruited through two possible mechanisms intended to maximize subject participation. In addition to the prospectively acquired collection described below, the Breast Center has assess to retrospective collections of frozen and fixed breast specimens acquired at our institution and also has potential access to additional prospectively collected resources through collaborative agreements.